Positive electrode material, its manufacturing method and lithium secondary battery
View Patent ↗The object of the invention is to provide positive electrode material in which a discharge rate characteristic and battery capacity are hardly deteriorated in the environment of low temperature of −30° C., its manufacturing method and a lithium secondary battery using the positive electrode material. The invention is characterized by the positive electrode material in which plural primary particles are flocculated and a secondary particle is formed, and the touch length of the primary particles is equivalent to 10 to 70% of the length of the whole periphery on the section of the touched primary particles.
1. A lithium secondary battery for a vehicle comprising:
a positive electrode made of a positive electrode material comprising:
plural primary particles flocculated to form a secondary particle, wherein a voidage of the secondary particle is 2.5 to 35%, the crystal orientations of c axes of 60% or more of the primary particles in the secondary particle are within 20 degrees, the secondary particle is represented as Li a Mn x Ni y Co z O 2 , and the secondary particle is composed of crystals having layer structure of composite oxide meeting 1<a≦1.2, 0≦x≦0.65, 0.33≦y<0.5, 0≦z≦0.65 and x+y+z=1;
a negative electrode; and
a non-aqueous electrolyte.
2. The lithium secondary battery for a vehicle according to claim 1 , wherein:
the mean diameter of the primary particle is 0.2 to 10 μm.
3. A lithium secondary battery for a vehicle according to claim 1 , wherein: the crystal orientations of c axes of 60% or more of the primary particles in the secondary particle are within 10 degrees.
4. A lithium secondary battery for a vehicle according to claim 1 , wherein the positive electrode material is made by a method comprising the steps of:
a step for grinding material powder including Li, Ni, Mn and Co,
a step for granulating the material powder by a spray dryer,
a step for burning the granulated material powder at 950 to 1100° C., and
a step for grinding the burnt granulated material powder.
5. A lithium secondary battery for a vehicle according to claim 1 , wherein the voidage of the secondary particle is 2.5 to 10%.
6. A lithium secondary battery for a vehicle according to claim 1 , wherein the voidage of the secondary particle is 2.5 to 5%.
7. A lithium secondary battery for a vehicle according to claim 1 , wherein the lithium secondary battery has a rechargeable capacity of approximately 10 mAh/g or more at −30° C. at 3.0V.